April 11, 2012
Bering Sea Seal Survey Undertaken By Russian And US Scientists
Researchers from Russia and the US want to estimate the number of seals in the Bering Sea region to learn what types of seals are in the region and how they are affected as sea ice, which some species depend on, shrinks due to climate change in the region.
The US National Oceanic and Atmospheric Administration (NOAA) is considering listing one or more species as threatened, writes Dan Joling of the Associated Press (AP). The agency is specifically reviewing the ribbon seal, and will also count spotted seals, a species it rejected for listing three years ago.
Surveying will last until May, with US and Russian researchers planning to fly a total of 30,000 square miles with thermal imaging cameras, along with high-resolution photography, which will pinpoint individual seals against the ice, writes Alex DeMarban for the Alaskan Dispatch.
Previous counts have been a challenge due to the expense of conducting research in such a remote location on species that spend time on both water and ice.
“The most novel thing about the survey is the pairing of two devices that have already been used to survey other marine mammals,” said Peter Boveng of the National Marine Mammal Laboratory in Seattle.
“Thermal or infrared cameras are good at detecting seals on ice, which are very warm relative to their surroundings, but not good at revealing the species of seals,” Boveng continued. “High-resolution digital photos are good for species identification, but very labor intensive for detecting and counting seals.”
To reduce the disturbance to seals, the surveys will be conducted using two planes from altitudes of 800-1,000 feet with flights lasting between five and seven hours and originating from Nome, Bethel, Dillingham, and St. Paul, Alaska.
Springtime in the Bering Sea is important not only for seals, but for many other species and the Alaska coastal communities that depend upon them.
Ringed seals, which were listed as threatened by the US Fish and Wildlife Service (FWS) in 2008, are the main prey of polar bears and are the smallest of the ice seals but the only ones that can live in completely ice-covered waters. They give birth to young in snow-covered lairs on sea ice.
Bearded seals give birth and raise pups on drifting pack ice over shallow water where prey such as crabs is abundant. When females give birth, they need ice to last long enough in the spring and early summer to successfully reproduce and molt.
The seal survey team will be communicating regularly with Alaska Native villages to ensure that the surveys do not conflict with subsistence hunting activities, particularly bowhead whaling around the communities on St. Lawrence Island and in Bering Strait.